得到当前窗口句柄或者指针2.txt

图像处理学习的一些心得

CWnd::GetSafeHwnd
This method obtains the window handle for a window. It returns NULL if the CWnd is not attached to a window or if it is used with a null CWnd pointer. 

HWND GetSafeHwnd( ) 
const; 
Return Value
Returns the window handle for a window. Returns NULL if the CWnd is not attached to a window or if it is used with a NULL CWnd pointer. 

Example
This is the example for the CWnd::SubclassWindow method.

// The following code shows how to subclass the edit control and list box
// controls inside a combo box. It uses WM_CTLCOLOR for subclassing.
// CSuperComboBox represents the combo box.
HBRUSH CSuperComboBox::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
   if (nCtlColor == CTLCOLOR_EDIT)
   {
      //Edit control
      if (m_edit.GetSafeHwnd() == NULL)
         m_edit.SubclassWindow(pWnd->GetSafeHwnd());
   }
   else if (nCtlColor == CTLCOLOR_LISTBOX)
   {
      //ListBox control
      if (m_listbox.GetSafeHwnd() == NULL)
         m_listbox.SubclassWindow(pWnd->GetSafeHwnd());
   }
   HBRUSH hbr = CComboBox::OnCtlColor(pDC, pWnd, nCtlColor);
   return hbr;
}

void CSuperComboBox::OnDestroy()
{
   // Unsubclass edit and list box before destruction.
   if (m_edit.GetSafeHwnd() != NULL)
      m_edit.UnsubclassWindow();
   if (m_listbox.GetSafeHwnd() != NULL)
      m_listbox.UnsubclassWindow();
   CComboBox::OnDestroy();
}

Requirements
  Windows CE versions: 1.0 and later
  Header file: Declared in Afxwin.h
  Platform: H/PC Pro, Palm-size PC, Pocket PC

如果类的转化有问题，即从CWnd*过来，需要用宏Dynamic_cast

如果要从指针转化为句柄，则可以用GetFromHandle()

对于在某个类中，比如是视图类或者是框架类，可以采用将本类的实例指针强制转换为CWnd型，比如(CWnd *)this，而后用它调用GetSafeHwnd( ) 

this->GetActiveWindow()
或者this->GetSafeHwnd();